William Somner (1598–1669) was an English antiquarian scholar, the author of the first dictionary of the Anglo-Saxon language.
He was baptised in the church of St. Margaret, Canterbury, on 5 November 1598, but according to a statement of his widow and surviving relatives, the date of his birth was 30 March 1606. His father held the office of registrary of the court of Canterbury, under Sir Nathaniel Brent, commissary. After passing through the free school at Canterbury, he became clerk to his father, and Archbishop William Laud soon advanced him to be registrar of the ecclesiastical courts of the diocese. The archbishop demanded of him a yearly report on the conduct of the clergy in the diocese, but this Somner failed to supply. Somner devoted his leisure to studying law and antiquities, and shooting with the long bow.
A royalist, after the execution of Charles I he wrote an elegy; subsequently he published another such poem, to which was prefixed the portrait of Charles I, from the Eikon Basilike. He was imprisoned for some time in Deal Castle for endeavouring to obtain subscriptions to a petition for a free parliament in 1659. At the Restoration he was preferred to the mastership of St. John's Hospital in the suburbs of Canterbury, and he was appointed auditor of Christ Church, Canterbury, by the dean and chapter. He died on 30 March 1669, and was buried in the church of St. Margaret, Canterbury. He was three times married, and left several children.
Somner acquired great reputation as an antiquary, and he numbered among his friends and correspondents Archbishops Laud and James Ussher, Robert Cotton, William Dugdale, Roger Dodsworth, Symonds D'Ewes, Edward Bysshe, Thomas Fuller, and Elias Ashmole.